Insects

Insects make up the largest and most varied group of an arthropods. Most reproduce easily, and there are insects adapted to any environment. Their bodies are protected by a form of armour. Arthropods are currently believed to be the only living things capable of surviving a nuclear winter. They have highly developed sensory orangs that enable them to see long distances. The diversity and sheer number of insect species, estimated at 1.5 million, are a testimony to their evolutionary success. They have been successful, in part, because they are small, need less food than larger organisms, and have extraordinary developed means of movement that keep them from being easy victims for predators.

The secret of Success

Sensory antennae, appendages on the head that can be used to chew, crush or grab, highly developed eyes on the sides of the head and pairs of jointed legs with functions that depend on the species - all are outstanding common features of insects and millipedes (subphylum Myriadpoda). Insects, also called hexapods, have six legs attached to the thorax. Myriapods are multi-segmented arthropods that have developed only on land.

The Better to See you With

Just as people without colour vision have a hard time understanding what colour is, it is impossible for humans to imagine what it is likes to see through the compound eye of an insect. These eyes are made of thousand of tiny rods called ommatidia, each one a composes small eye connected directly to the brain. Scientists theorized that the insect's brain composes the images received from each ommatidium, enabling it to perceive movement in any possible direction - in some species, even from behind.

Types of Mouths

Far from being a mere opening, the mouth is usually one of the most complex parts of an insect's body. The simple oral appendages of the most primitive forms were gradually modified so that this zoological group has been able to expand its diet. Thus, a hunter's mouth is totally different from that of a sucking insect or a leafeater, such as the locust.

Great Walkers

Etymologically speaking, myriapod means 'many feet'. The term refers to two very different classes of invertebrate: class Chilopoda and class Diploda, better known as centipedes and millipedes. All are animals divided into segments. Centepedes, most of which are carnivores, have a pair of legs on each segment, and millipedes have two pairs of legs per segment. These invertebrates (which are not insects) have so many legs that, to walk, they must use a highly sophisticated timing mechanism that seems to follow mathematical principles.

High-Quality Jumpers

Fleas are well known for their extraordinary jumps. When they are adults, these small, wingless insects take advantage of their jumping ability to hunt for their food, the blood of birds and mammals. They are ectoparasites of dogs, cats and chickens, which keeps them present in our daily lives. They invariably bite their hosts and suck the blood that circulates through their skins.

The Art of Flying

One of the most basic adaptations of insects has been their ability to fly. Most have two pairs of wings. Beetles (order Coleoptera) use one pair to fly and one pair for protection. For example, the rounded body of a ladybird is nothing more than the covering for a very sophisticated flight system. It makes these small beetles, which are harmless to humans, great hunters in the insect world.

Metamorphosis

Metamorphosis is the change of shape that insects undergo as they grow. There are two types of transfomations: complete, like that of monarch butterflies, and incomplete, like that of dragonflies or grasshoppers. Insect with complete metamorphosis pass through an immobile state (called the pupal, or with complete metamorphosis pass through an immobile state(called the pupal, or chrysalid, phase) in which their body is transformed by harmones within a cocon.

Order and Progress

Ants are one of the insects with the highest social organization. In the anthill, each inhabitant has a job to do. The head of the family is the queen, the only one that reproduces. All the rest of the ants are her offspring. During mating, queens and drones (males) from various colonies mate ont the wing. The queens need to mate several times, because the sperm they receive will have to last their lifetime.

Goal: Survival

Evolution has moulded some striking traits into living beings. In particular, some insects, disguised as branches or leaves can escape notice so it can hunt or hide from predators. To avoid being attacked, other insects developed colours and shape that deceive other animals and keep them from attacking. Hiding and showing off are two opposite strategies that have been favouring the survival of the fittest for millions of years.